1. Field of the Invention
The invention relates to a welded rotor of a turbo engine.
2. Brief Description of the Related Art
In modern turbo machines, the cooling of thermally highly stressed units is becoming ever more important. In particular, this includes the cooling of the rotor and rotor blades which require a high cooling intensity. According to one method, it is known that part of the compressed air is branched off for cooling purposes and is returned after cooling to the operating mass flow. Since modern gas turbines per se have only a limited air supply, this branching off of air for cooling purposes is always connected with a certain degree of lost effectiveness. Recently, therefore, there have been suggestions for cooling thermally loaded aggregates of a gas turbine with other cooling media, e.g., a cooling medium that is preferably available in an adequate amount and with cooling quality.
When cooling the rotor and then transferring the cooling medium to the rotor blades of the gas turbine, it must be assumed that in such a rotor-internal cooling system, in particular if cooling steam is being used, it is easy for stagnating steam spaces to be created in which deposits, accumulations of condensation during start-up, as well as corrosion processes then necessarily may occur during standstill. This additionally causes the highly stressed parts to have a tendency for stress corrosion, reducing the availability of the system.
The described risks during steam cooling are even more accentuated for welded rotors, i.e., rotors consisting of disks welded together, in particular if less ductile types of steel which tend towards stress corrosion cracking are used.
In addition, it must be taken into consideration that the rotor-internal channels through which the cooling medium flows must be provided with intermediary annular cavities in the plane of the radially welding seams, and where these cavities are absolutely required so that the cooling medium can flow through them and be transferred to the cooling rotor blades, whereby the type of welding technology used for the transition of the radially or quasi-radially extending welding seams near these cavities is important for the operating quality of such a rotor.